The jewel would be the black soulstone. For all of those who don't know it the black soulstone is what should ultimatley ressurect Tathamet which is all 7 evils combined in one soulstone. "The prime evil" isn't diablo its Tathamet they accidentally fucked up part of the story with that. I believe Adria will find the soulstone and place into tathamets carcass before we kill her whihc will leave the next game open for killing tathamet.

I don't actually think so. The prime aspects of good and evil has shattered and I do not think they can be made whole again (the aspect of good, that dragon, he became the silver spire).
But apart from that, diablo embed the black soulstone into his flesh (or Adria actually did it to Leah). Then you (yeah, you) destroyed Diablo and thus the Black Soulstone. Or so I assume. There is no reference to you destroying it but none is there any reference to it being still in once piece.... And the Prime Evil was indeed Diablo for a moment, as he had all evils combined within himself, thus making him the prime evil.

And a small little detail; Shen (I do so love that character) is talking about a demon called Dirgest possessing the gem is he looking for

Then you (yeah, you) destroyed Diablo and thus the Black Soulstone. Or so I assume. There is no reference to you destroying it but none is there any reference to it being still in once piece....

I wouldn't know where you'd have to go, but I'm pretty sure Blizzard personnel have come forth and explicitly clarified that the BS is still intact. (You can see it falling through the clouds or whatever if you look close) Just put in my CE Behind the Scenes DVD, here is the Storyboard showing the soulstone is definitely still in one piece after Diablo disintegrated.

"But the Black Soulstone is flawed and cannot contain that many demons for long. We must capture Azmodan within it and shatter it... lest all these Evils be reborn."
Yep.

The writing for Diablo III was pathetic, but if the black soulstone just "happened to go overlooked as it was kicked through the gutters of heaven by many a sandal-clad foot," that would be the biggest load of horseshit known to writing. That's like a preemptive deus ex machina coupled with a spell of multi-dimensional global amnesia.

At least one of the expansions should center around Imperius going rogue and waging a war of extermination on anyone with the slightest hint of Nephilim blood. Your character could travel to the origin places of all the characters from D2 and D3, both protecting and avenging those who would fall within harm's way. Imperius could use his powers to summon other creatures of heaven, but twisted to his own ends. It would be like starting the game series over with heaven as the enemy and no convoluted and implausible retconning.

The writing for Diablo III was pathetic, but if the black soulstone just "happened to go overlooked as it was kicked through the gutters of heaven by many a sandal-clad foot," that would be the biggest load of horseshit known to writing. That's like a preemptive deus ex machina coupled with a spell of multi-dimensional global amnesia.

At least one of the expansions should center around Imperius going rogue and waging a war of extermination on anyone with the slightest hint of Nephilim blood. Your character could travel to the origin places of all the characters from D2 and D3, both protecting and avenging those who would fall within harm's way. Imperius could use his powers to summon other creatures of heaven, but twisted to his own ends. It would be like starting the game series over with heaven as the enemy and no convoluted and implausible retconning.

Well, Diablo was the prime evil but it is certainly not the "Prime Evil" as described by the book of Cain as the body of Tathamet is now Hell itself and all the 7 evils are just the heads, not the whole.

The thing about D3 is that Metzen made clear (but I can't find any references to it) is that nor heaven nor hell is the good way, it's about having the opportunity to choose (also remember the first iteration of D3 at Blizz North with the angelic / demonic wepons).
The Eternal Conflict raged on for millenias and could never end as Evils or Archangels always reincarnate in some way. The battle is just delayed.

The Black Soulstone was meant to contain both angels and demons - and I mean CONTAIN - thus leaving only humans to direct themselves from good or wrong.

I agree that Imperius should go rogue because HE is the embodiment of fanaticism.
But more importantly, there could be no Heaven without Hell as I described before because Heaven would go insane over "Ancient Rules of Inactions and Fanatic stuff etc etc"...

Another thing is that Angels / Demons are supposed to be bound to their fate. They should never ever go the opposite way by Force of Will (to differenciate from Corruption like Izual).
But, and that's the issue, the Prophet (from the enchantress) did. This means there is hope for every entity to use free will.

I know Inarius and Lilith did before too. So what? the Eternal Conflict being about "Hellish / Heavenly Nature" is all bullshit and just needed "us" (One Nephalem) to end it?
Seems bad writing to me...

I think the prophet is going to be more along the lines of Malthael then Inarius. For one, I got the impression the Enchantress is from after the Sin War (and Inarius has been in Hell since then). For two, it just wouldn't have been his style, from what we saw in the Sin War Trilogy (you know, aside from the name "Prophet").

The writing for Diablo III was pathetic, but if the black soulstone just "happened to go overlooked as it was kicked through the gutters of heaven by many a sandal-clad foot," that would be the biggest load of horseshit known to writing. That's like a preemptive deus ex machina coupled with a spell of multi-dimensional global amnesia.

I took it as when Diablo died, he fell off the spire, and they weren't able to retrieve the BS. Also, it's been pretty clear that the Angels aren't exactly genre savy, I think it's pretty consistent if they think the threat is over, at least for now.

At least one of the expansions should center around Imperius going rogue and waging a war of extermination on anyone with the slightest hint of Nephilim blood. Your character could travel to the origin places of all the characters from D2 and D3, both protecting and avenging those who would fall within harm's way. Imperius could use his powers to summon other creatures of heaven, but twisted to his own ends. It would be like starting the game series over with heaven as the enemy and no convoluted and implausible retconning.

I really hope it's not primarily about Imperius. I feel he's boring and one dimensional. Also, we already clobbered Diablo, who clobbered Inarius (twice). It'd be a bit of a stretch to say that he's actually tougher to beat then Diablo (united with the other evils).

I think we have more than enough with closing up the Templar's, Scoundrel's, and Shen's story lines, not to mention what they've already said about Adria. And Maltheal.

That said, I wouldn't mind if we do fight Imperius, but he ends up being a mini-boss for Adria/Lillith/whomever ends up being the big bad(s) of the expansion.

And to whoever was talking about Andariel/Duriel still being around, they aren't. They got pulled into the soulstone along with Baal, Diablo, and Mephisto. Otherwise Diablo wouldn't have been THE prime evil, cause he'd have been missing those two.

Regarding expansions, I'm not sure if this was brought up, but in the Collector's Edition interviews with the game developers, they did say this (paraphrased):

They do want to explore the salvation of Leah's soul after she becomes Diablo and her body is essentially destroyed at the end of the game, simply because it feels like the right thing to do from a traditional storytelling stance.

I friend of mine think that the next expansion(or third, it's not really important which one) could actually be about Heaven trying to destroy Sanctuary. In the Sin-War only Tyrael voted against the destruction of Sanctuary, however he isn't an angel anymore so it wouldn't be suprising that eventually the Angiris Council put him appart. In the small video Blizzard released we saw that Imperius can actually not give a single fuck about the council (you know when he "kills" diablo without waiting for the vote) so, again, it wouldn,t be too crazy to think that Imperius, since Tyrael isn't an angel anymore, try to raise an army and see the destruction of sanctuary.

In the opening cain says "justice shall fall", this is Tyrael obviously, and then he says "the army of light and shadow will clash upon the field of eternity". So far only army of shadow actually did something. The light didn't do anything.

I friend of mine think that the next expansion(or third, it's not really important which one) could actually be about Heaven trying to destroy Sanctuary. In the Sin-War only Tyrael voted against the destruction of Sanctuary,

This is not the case, it was a 3:2 vote, Auria andItherael voted to keep sanctuary while Imperius and Malthael wanted to destory it. Tyrael was impressed by the self-sacrifice of the Nephanem and thus decided to vote to keep sanctuary as well and as a result he and Imperius were on odds ever since. Tyrael surely is a good guy but he might get too much credit on this topic.

I'm convinced the 'prophet' we hear our Enchantress speak of is Maltheal, not Inarius. Tathamet won't be seen as his destruction along with Anu's is what created the Burning Hells and the High Heavens respectively.

All signs point to the expansion(s) dealing with the whereabouts of the Black Soulstone, the pursuit of Adria, the corruption of Imperius and the restoration of Leah's soul.